sculpting terrain of, and Importing a heightmap with difference of more that 50

[CatmanFS]

though the brush settings and seems like the datatype responsible for terrain height goes from 0-255 importing a heightmap seems to not work without clamping either top or bottom, somehow i was able to do this but without whatever trickery i managed to use simply exporting an upper-scaled heightmap and re-importing it wont work. Sculpting the terrain of that map and trying to set water height also seems to behave strangely.